Uca (Austruca) albimana ( Kossmann, 1877 )

Naderloo, Reza, Türkay, Michael & Chen, Hui-Lian, 2010, Taxonomic revision of the wide-front fiddler crabs of the Uca lactea group (Crustacea: Decapoda: Brachyura: Ocypodidae) in the Indo-West Pacific, Zootaxa 2500, pp. 1-38 : 4-6

Uca (Austruca) albimana ( Kossmann, 1877)

( Figs. 1 a–l, 4a, 6a–b)

Gelasimus annulipes var. albimana Kossmann, 1877: 53 –54.

Uca annulipes — Nobili 1906a: 150 –151; 1906b: 311 (in key), 312. — Laurie 1915 (in list): 416. — Balss 1924: 15. — Hornby 1997: 15.

Uca (Celuca) lactea annulipes — Crane 1975: 299, 301, 611. [part.: Red Sea material].

Uca (Celuca) lactea albimana — Lewinsohn 1977: 61 –63.

Uca lactea — Hogarth, 1989: 114 –115. — Ismail & Ahmed 1993: 158 (in list).

Uca lactea annulipes — Hywel-Davies 1994: 37, 48.

Uca annulipes albimana — Apel & Türkay 1999: 133. — Apel 2001: 114.

Uca albimana — Shih et al. 2009: 377.

Lectotype. 1 male [(SMF 9709) CL 6.8, CB 12.3, Ch.L 19.8 mm] Red Sea, 1874-75, leg. R. Kossmann.

Paralectotypes. 1 male, 1 female (SMF 17145), data as lectotype.

Other material. Red Sea: 2 males ( ZMH K2905), vend. Mus. Goddefroy; 1 male, 6 females ( SMF 5698), Egypt, Kuseir, 0 5.1965, leg. E. Linsenmair; 1 male ( SMF 26011) Egypt, Manteqat al Bahr al Ahmar, Safaga S. Hurghada, mangroves, 20.09.1994, leg. C. Rhode & N. Dressler; 1 female ( SMF 26012), Egypt, Manteqat al Bahr al Ahmar, 25° 52'N 34° 25'E, mangroves, 22.09.1994, leg. C. Rhode & N. Dressler.

Gulf of Aden: 1 male, 1 female ( SMF 5646), Ethiopia, Massaua, 11.1826–02.1832, 1eg. E. Rüppell; 1 male ( MNHN B11874), Yemen, Perim Island, 1897, leg. M. Jousseaume; 5 males (NHM 1974:92) Jebel Hadd, near Aden, 10.1966, K. England; 1 male ( MNHN B11876), Djibouti, Obock, 1897, 1eg. M. Jousseaume; 216 males, 18 females ( ZMH K38114 ), Djibouti, winter 1909/10, 1eg. E. Wache; 2 males ( SMF 24497) Djibouti, Godoriyah, landward ridge of mangroves, 24.06.1996, leg. U. Zajonz & F. Krupp.

Arabian Sea: 3 males (NHM 1988:55), Oman, Dhofar, 20 km N. of Ras Sawqirah, Khor Fakr, 18° 19'N 56° 36'E, 10.11.1985, 1eg. J.B. Clarke; 1 male (NHCY 83), Yemen, Sokotra, N. coast, Khawr Qariyah, 12° 38.054'N 54° 12.568'E, muddy-sand, 10.02.1199, N. Simoes; 3 males, 1 female (NHCY 84), Yemen, Sokotra, W. coast, 12° 41.099'N, 53° 28.476'E, muddy-sand, bank of Wadi, 10.03.1999, M. Apel; 2 males (NHCY 85), Yemen, Sokotra, bank of Khawr, 12° 35.976'N 53° 46.44'E, muddy, 0 4.02.1999, N. Simoes; 3 males, 1 female (SMF 36907) Yemen, Sokotra, N. caost, Qadub-Mori, near Mori Lagune, 12° 38.446'N, 53° 56.137'E, muddysand, 05.02.1999; N. Simoes; 1 male (SMF 36908) Yemen, Sokotra, Khawr Qarayah, 12° 38.425'N, 54° 13.338'E, 0 7.04.1999, M. Apel; 7 males, 2 females (1 ovig.), 1 juv. (SMF 36909), Yemen, Sokotra, Qualansiyah Lagune, 12° 41.904'N, 53° 30.041'E, muddy-sand, 12.04.1999, M. Apel.

Gulf of Oman: 13 males, 1 female (SMF 26013), UAE, Fujairah, Khor Kalba, 25° 01'N 56° 21'E, mangroves, intertidal flat, sandy-mud substrate, 0 1.07.1995, M. Apel; 1 male (SMF 26014), UAE, Fujairah, Khor Kalba, 25° 01'N 56° 21'E, mangroves, intertidal flat, sandy-muddy substrate, 0 1.07.1995, M. Apel.

Persian Gulf: 3 males (SMF 26018), UAE, Ras al Khaimah, 25° 50'N 55° 00'E, sandy flat, supralittoral zone among Salicornia sp., 11.07.1995, M. Apel; 9 males (SMF 26015), UAE, Umm al Qaiwain, khor, 25° 35'N 55° 34'E, 0 9.07.1995, M. Apel; 1 male (SMF 26032), UAE, Ajman, 25° 25'N 55° 29'E, intertidal flat, loose muddy substrate, among halophyte, 10.07.1995, M. Apel; 1 male, 1 female (SMF 26017), UAE, Ras al Khaimah, mangroves of N. Rams, 25° 50'N 55° 00'E, sandy-mud substrate, supralittoral zone, 10.07.1995, M. Apel.

Unknown locality: 3 males (MNHN), 0 2.1933, leg. J. L. Dantan.

a, infraorbital region of male; b, infraorbital region of female; c, major chela, outer surface; d, major chela, inner surface; e, merus of major chela, outer surface; f, merus of major chela, inner surface; g, minor chela, outer surface; i, minor chela, outer surface; k, tip of G1, mesial surface; j, tip of G1, lateral surface. l, genital opening of female.

Diagnosis. Front broad. Anterolateral borders of carapace moderately convergent. Major male chela palm without a supramarginal groove adjacent to lower border. G1 with palp relatively short, not reaching to base of horny endpiece; this last one flat, with flanges not inclined, longer than broad, suture displaced ventrally; terminal opening marked by a more or less distinct notch.

Redescription. Front broad, about 1/6.5 times as broad as carapace. Ventrolateral margin of carapace moderately convergent, distinctly crested, joining to posterolateral margin at base of exorbital triangle; posterolateral margin distinctly crested, extending curvedly backwards, ending at level of middle cardiac region; posterolateral striae short. Exorbital angle acutely triangular, directed forwards and inwardly; upper orbital margin sinuous, with two crests bordering narrow eyebrow; eyebrow getting narrower outwardly, inner part less than 1/2 breadth of eyestalk in adjacent region; lower orbital margin regularly granulate, granules becoming larger outwardly ( Fig. 1 a), that of the paralectotype female with additional small granules, on middle part, at inner side of large granules ( Fig. 1 b).

Pterygostomian region ( Fig. 1 a) with regular feather-shaped bristles, becoming glabrous towards lower orbital region, two short longitudinal lines of bristles on anterior-inner portion.

Third maxilliped with merus about 1/3 length of ischium; longitudinal broad groove on outer surface of ischium and merus close to inner margin, bordered with short setae; long setae on inner margin of ischium and merus.

Major chela merus with transverse ridges on upper margin, finely granulate, becoming irregular distally; lower margin denticulate ( Fig. 1 e), denticles small, becoming larger distally; inner surface ( Fig. 1 f) with patch of relatively large granules distally on upper portion. Carpus about 1.5 times as long as broad, inner upper margin denticulate, small patch of feather-shaped setae on lower proximal and upper distal portions of inner surface. Outer surface of palm ( Fig. 1 c) smooth, without supramarginal groove; lower margin weakly granulate, with low granules, upper margin granulate, with relatively small granules; inner surface ( Fig. 1 d) with high oblique tuberculate ridge, tubercles large, becoming smaller distally; proximal ridge at dactylus base with large granules, distal ridge parallel to proximal one, with granules, low, relatively small. Dactylus about 1.3 to 1.4 times as long as palm, higher than fixed finger; proximal, median teeth on cutting edge of both fingers, median teeth relatively large, that of fixed finger slightly larger; fixed finger with subdistal tooth.

Small chela ( Figs. 1 g, i) with smooth ridge on outer surface, extending from lower distal part of palm to two third of fixed finger; cutting edge without tooth, gap between fingers as wide as adjacent dactylus, fixed finger slightly wider than dactylus.

Merus of walking legs with finely granulated transverse ridges on anterior margin, posterior margin minutely serrated; propodus 1.2 times as long as carpus; dactylus conical, as long as propodus; last leg with propodus as long as carpus; anterior margin of carpus and propodus slightly granulate.

Male abdomen tapering from segment 2 to 5, segment 6 with lateral margin nearly straight, length of segments 3-5 subequal.

G1 ( Figs. 1 j, k) with stem slightly bent in posterolateral direction, palp not reaching to base of horny endpiece; latter slightly longer than wide, distal margin convex, dorsal lobe large, reaching slightly beyond ventral lobe; terminal opening of sperm channel ventrally subdistal, in middle line of endpiece lobes; scarce feather-shaped setae along lateral margin, distally becoming longer and relatively dense, scarce short setae on palp.

Genital opening of female: direction of opercle edge parallel to median line of sternum.

Median tooth plate of the gastric mill ( Fig. 4 a) with 8 teeth, small gaps between them, two first ones massive, different in shape, 3–8 decreasing in size posteriorly, last one distally attached to basal plate; lateral tooth plate with 20–22 comb-shaped teeth.

Distribution. Red Sea, Gulf of Aden, Socotra, Arabian Sea, Oman (Dhofar), south Gulf of Oman, southeastern Persian Gulf.

Remarks. Crane (1975), like former authors, treated the present species as a synonym of U. annulipes . Lewinsohn (1977) was the first to point out the differences between both and thus separated the Red Sea populations under the subspecific name U. lactea albimana . We agree with the differences cited by Lewinsohn (1977), namely the lack of a supramarginal groove on the major chela and lack of a patch of setae on the lower distal portion of merus of the same chela in all specimens from the Red Sea and specimens from outside the Red Sea. Furthermore, a distinct difference is the median tooth of the gastric mill. U. albimana has 8 teeth on the median plate, whereas U. iranica has 6, which confirms the clear difference between these two species. We therefore consider both of them as having species rank. Regarding the median tooth of the gastric mill, U. albimana is more closely related to U. annulipes , as this last species has also 8 teeth on the median tooth ( Figs. 4 a, b). The most prominent difference is the shape of the second tooth, which is nearly elliptical in U. annulipes .

The material from Oman, Gulf of Oman, Persian Gulf and M. Jousseaume's material from Djibouti (Obock) belong to the typical U. albimana . This species is remarkably small-sized (the largest male [SMF 5698] from the Red Sea measures CL 8.5, CB 15.5, Ch.L 25.00 mm) in comparison to its more closely related and partly sympatric congeners U. annulipes and U. iranica . Lewinsohn (1977) also mentioned the small size of U. albimana in comparison to U. annulipes . This species are sympatric, with U. iranica in the southeastern Persian Gulf and western Gulf of Oman, but easily distinguished from U. iranica , apart from its fully different median tooth of the gastric mill, by having moderately convergent lateral margins, which are very slightly convergent, or nearly straight in U. iranica . Genetic evidence presented by Shih et al. (2009) supports our morphological findings as to the differentiation of these two species from each other and from U. annulipes .

Figures

FIGURE 1. Uca albimana (Kossmann, 1877): a, c – f, i – j, lectotype male (SMF 9709); b, g, paralectotype females (SMF 17145); l ovigerous female (SFM 5698), Egypt.

FIGURE 4. Median tooth plate of the gastric mill, ventral face. a, Uca albimana (Kossmann, 1877), male (SMF 26018); b, Uca annulipes (H. Milne Edwards, 1837), male (SMF 9107).